Composite article of magnesium material and resin component, and method for producing said composite article

ABSTRACT

To be able to efficiently produce a resin component on a magnesium material. [Solution] A composite article is produced by forming an anodic oxide film on one surface of a magnesium material as a consequence of immersing the magnesium material into an electrolyte solution and applying a voltage, and by joining a resin component to the magnesium material by using the anodic oxide film. The electrolyte solution is formed by dissolving sodium dihydrogen phosphate and sodium hydroxide in pure water. The weight mixture ratio (R1) of sodium dihydrogen phosphate and sodium hydroxide is 1:2≦R1&lt;2:1, and the voltage is between  20  and  50  V.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to a composite article of magnesium material, and method for producing said composite article.

2. Description of Related Art

Using a mould for insert forming is a well-known method to join a resin component with metallic material, in detail a metallic component made of iron or steel is inserted into the cavity of the mould, and under this state, molten resin is injected into the cavity so that a portion of the metallic component is embedded inside the resin component of an expected shape.

In addition, to join aluminum material with a resin component, a well-known method is to form an anodic oxide film on the surface of the aluminum material with multiple pores with diameters of over 25 nm, and cause part of the resin to bite into the pores of the anodic oxide film through a method like injection forming.

PREVIOUS LITERATURES

Patent Literature 1-Descriptions of International Publication No. 2004/055248

SUMMARY OF THE INVENTION

In recent years, to obtain components with light weight and high strength, magnesium material is frequently used to replace aluminum material, and there is a need to join magnesium material with a resin component. In view of this need, the objective of the present invention is to provide a method to efficiently produce a composite article with magnesium material and resin component.

To overcome the afore-mentioned problem, the present invention provides a method to produce a composite article with magnesium material and resin component, with its characteristics residing in the inclusion of: a process to immerse the magnesium material into an electrolyte solution formed by dissolving sodium dihydrogen phosphate and sodium hydroxide in pure water; a process to apply a voltage upon said magnesium material immersed with said electrolyte solution, so as to form an anodic oxide film on the surface of said magnesium material; and a process to fill part of the resin component into the multiple pores on said anodic oxide film so as to join said magnesium material with said resin component.

Furthermore, in the above production method, the weight mixture ratio R1 of said sodium dihydrogen phosphate and said sodium hydroxide is 1:2≦R1<2:1.

Furthermore, in the above production method, the voltage applied on said magnesium material is 10V˜50V.

Furthermore, in the above production method, the weight proportion of said sodium dihydrogen phosphate and said sodium hydroxide is 1:1.

Meanwhile, the present invention provides a composite article, which is a finished product produced by means of the above production method.

Based on the method disclosed in the present invention to generate an anodic oxide film on the magnesium material through an electrolyte solution formed by mixing sodium hydroxide and sodium dihydrogen phosphate, the resin component can be stably joined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A sectional view of the structure of a composite article with magnesium material and resin component as an embodiment of the present invention.

FIG. 2: A process flow chart of the production method of a composite article with magnesium material and resin component as an embodiment of the present invention.

FIG. 3: A sectional view of the anodic oxide film formed on the magnesium material in the embodiment of the present invention.

FIG. 4: A cross-sectional view of one example of the method to join the resin component with the magnesium material in the embodiment of the present invention.

FIG. 5A: A schematic view of the process embodiment to form an anodic oxide film on the magnesium material in the embodiment of the present invention.

FIG. 5B: A schematic view of the process embodiment to form an anodic oxide film on the magnesium material in the embodiment of the present invention.

FIG. 6A: A schematic view of the process embodiment to form an anodic oxide film on the magnesium material in the embodiment of the present invention.

FIG. 6B: A schematic view of the process embodiment to form an anodic oxide film on the magnesium material in the embodiment of the present invention.

FIG. 7A: A schematic view of the process embodiment to form an anodic oxide film on the magnesium material in the embodiment of the present invention.

FIG. 7B: A schematic view of the process embodiment to form an anodic oxide film on the magnesium material in the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The sectional view in FIG. 1 discloses a composite article 1, which has a structure made up of a magnesium material and an anodic oxide film 3 generated on surface 2A of one side of the magnesium material to join with a resin component 4.

The method to produce a composite article with magnesium material and resin component is briefly described based on the process flow chart in FIG. 2.

Firstly, take Step S101 to die-press the magnesium material 2 to form the required shape. Then, take Step S102 to generate a joining film on the magnesium material 2, and consequently form a porous anodic oxide film 3.

Furthermore, take Step S103 to join the resin component 4 on the area formed with an anodic oxide film 3. As shown in FIG. 1, the resin component 4 bites into the pores 6 on the anodic oxide him 3, and joins with the magnesium material 2. In this way, a composite article 1 with magnesium material 2 and resin component 4 is produced.

Furthermore, take Step S104 to conduct an after-treatment of the composite article 1. The after-treatment is to coat the other surface 28 of the magnesium material 2. Alternatively, it is also fine to finish the processing without applying Step S104.

Below is a detailed description of the process to form a joining film in Step S102.

Firstly, degreasing treatment and neutralizing treatment of the magnesium material 2 are carried out as needed. Then, put the magnesium material 2 into an electrolytic bath. The electrolytic bath contains an electrolyte solution formed by dissolving a strong alkaline substance and a weak acid substance in pure water. The strong alkaline substance can be, for example, sodium hydroxide. The weak acid substance is sodium phosphate, and more specifically, sodium dihydrogen phosphate (NaH₂PO₄). The weights of sodium hydroxide and sodium dihydrogen phosphate dissolved in 40L of pure water respectively range from 1 kg to 3 kg. Furthermore, the temperature of the electrolyte solution is adjusted to be 30° C.˜40° C. The magnesium material 2 is used as the anode, while the cathode is something like a stainless steel plate. Moreover, within a voltage range of 10V˜50V, electrical decomposition is carried out through a direct current method for 3˜10 minutes, for example.

In this way, as shown in the sectional view in FIG. 3, a porous anodic oxide film 3 of approximate thickness of 0.5˜1.5μ is formed on surface 2A of one side of the magnesium material 2. The anodic oxide film 3 includes a porous layer 5A with thin and long pores 6 formed on its surface and a thin and fine insulating layer 5B located between the bottom of the porous layer 5A and the metal surface. In addition, the multiple pores 6 formed on the surface of the anodic oxide film 3 have diameters of 20˜100 nm. After the anodic oxide film 3 is formed, the magnesium material 2 is cleaned with pure water and dried by hot wind.

Furthermore, the process in Step S103 to join the resin component 4 and the magnesium material 2 is described below.

FIG. 4 discloses an example of the injection forming machine used in the production process of the present invention. The injection forming machine 20 is installed with a separable mould 21 having an upper part and a lower part. Between the lower mould 21A and the upper mould 21B, a space 22 is formed to fit the magnesium material 2. Furthermore, the upper mould 21B is made up of a cavity 23 in a shape to match that of the resin component 4, and a gate 25 for the resin 24 to pass and fill into the cavity 23. In addition, the gate 25 is connected to a supply source of the resin 24, which is omitted in the drawing.

The resin 24 can be any resin like PP (polypropylene), PE (polyethylene), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide) or silicon rubber. In addition, considering the difference of linear expansion between magnesium material 2 and resin 24, the resin material of the resin component produced through the afore-mentioned injection forming can provide a flexibility to absorb the difference of linear expansion, and the resin has an excellent elasticity up to 10000 Mpa. There are also options of resins with-good resistance to hot water and drug. Suitable resins 24 include olefin resins like PBT, PE or PP.

To form the resin component 4, open the mould 21, fit the magnesium material 2 inside the space 22. Face the anodic oxide film 3 of the magnesium material 2 upward, i.e., face the anodic oxide film 3 toward the gate 25. After closing the mould 21, press and fill the molten resin 24 into the cavity, and meanwhile fill the resin into the multiple pores of the anodic oxide film 3.

After this, open the mould, and a composite article 1 as shown in FIG. 1 is obtained. The composite article 1 has a structure with the resin 24 forming the resin component 4 biting into the multiple pores 6 of the anodic oxide film 3.

In the composite article 1 produced through the above method, the joining strength between the magnesium material 2 and the resin component 4 is very good. The compressive strength measured by a stress testing machine is higher than 20N. In addition, in the process to join the resin component 4 and the magnesium material, heat pressing or other methods are all applicable.

As described above, the embodiments of the present invention use an electrolyte solution formed by mixing sodium hydroxide and sodium dihydrogen phosphate to generate an anodic oxide film 3 on the magnesium material 2, so that it can join with the resin component 4.

Below are detailed descriptions of the present invention based on the embodiments:

In the embodiment disclosed in FIG. 5A, the electrolyte solution is formed by dissolving 2 kg of sodium dihydrogen phosphate into pure water 401. The temperature of the electrolyte solution is 35° C., and the conduction time is 5 minutes. The voltages are within the range of 10V˜50V. A test is conducted at each interval of 10V. The result is: under any voltage, the surface of the magnesium material 2 is eroded and deteriorated by the electrolyte solution, but no anodic, oxide film 3 is formed. Hence, it is known that, sodium dihydrogen phosphate alone is not suitable for formation of the anodic oxide film 3.

In the embodiment disclosed in FIG. 5B, the electrolyte solution is formed by dissolving 2 kg of sodium dihydrogen phosphate and 1 kg of sodium hydroxide in pure water 401. The temperature of the electrolyte solution is 35° C., and the conduction time is 5 minutes. The voltages are within the range of 10V˜50V. A test is conducted at each interval of 10V. The result is: under any voltage, the surface of the magnesium material 2 is eroded and deteriorated by the electrolyte solution, but no anodic oxide film 3 is formed. Hence, it is known that the above conditions are not suitable for formation of the anodic oxide film 3.

In the embodiment disclosed in FIG. 6A, the electrolyte solution is formed by dissolving 500 g of sodium hydroxide in pure water 401. The temperature of the electrolyte solution is 35° C., and the conduction time is 5 minutes. The voltages are within the range of 10V˜50V. A test is conducted at each interval of 10V. The result is: when applying a voltage of 10V, the surface of the magnesium material 2 is deteriorated, while when applying voltages of 20V, 30V, and 40V, an anodic oxide film 3 can be formed. Based on the anodic oxide film 3 formed under such conditions is, the resin component 4 is joined with the magnesium material 2, and the joining strength is investigated through a stress test. Under different conditions with voltage application of 20V, 30V, and 40V, the joining strength averages of the resin component 4 are respectively 20N, 50N, and 30N. However, there are possibilities that the joining strength is not even or the joint is incomplete. Moreover, when applying a voltage of 50V, the surface of the magnesium material 2 is not deteriorated, therefore the resin component 4 cannot join with it. Hence, it is known that this kind of electrolyte solution is not suitable for formation of the anodic oxide film 3. In addition, the more quantity of sodium hydroxide dissolved in pure water, the more obvious is the deterioration of the magnesium material 2.

In the embodiment disclosed in FIG. 6B, the electrolyte solution is formed by dissolving 1 kg of sodium dihydrogen phosphate and 2 kg of sodium hydroxide into pure water 401. The temperature of the electrolyte solution is 35° C., and the conduction time is 5 minutes. The voltages are Within the range of 10V˜50V. A test is conducted at each interval of 10V. The result is: when applying a voltage of 10V, the surface of the magnesium material 2 is deteriorated, and there is a condition of incomplete joint. The resin component 4 of the composite article 1 produced based on the anodic oxide film 3 formed when applying a voltage of 20V has a joining strength average of 60N. Similarly, when applying a voltage of 30V and 40V, the joining strength average is respectively 50N and 30N. When applying a voltage of 50V, the surface is not deteriorated, therefore the joint is impossible. Hence, it is known that, this kind of electrolyte solution can form an anodic oxide film when the applied voltage is between 20V and 40V, and the resin component 4 can be joined.

In the embodiment disclosed in FIG. 7A, the electrolyte solution is formed by dissolving 2 kg of sodium dihydrogen phosphate and 2 kg of sodium hydroxide in pure water 401. The temperature of the electrolyte solution is 35° C., and the conduction time is 5 minutes. The voltages are within the range of 10V˜50V. A test is conducted at each interval of 10V. The result is: when applying a voltage of 10V, the joining strength average of the composite article 1 is 40N. Furthermore, when applying a voltage of 20V, 30V, 40V, and 50V, the joining strength average of the composite article 1 is respectively 50N, 70N, 70N, and 20N. The surface of the magnesium material 2 is deteriorated when applying a voltage of only 10V or 20V, while the surface is not deteriorated when applying a voltage of 30V. Hence, this kind of electrolyte solution can provide stable joint of the resin component 4 under a voltage between 10V and 50V. Furthermore, from the view of the surface state and joining strength of the magnesium material 2, it is known that an applied voltage between 30V and 40V is an ideal condition.

In the embodiment disclosed in FIG. 7B, the electrolyte solution is formed by dissolving 3 kg of sodium dihydrogen phosphate and 3 kg of sodium hydroxide in pure water 401. The temperature of the electrolyte solution is 35° C., and the conduction time is 5 minutes. The voltages are within the range of 10V˜50V. A test is conducted at each interval of 10V. The result is: when applying a voltage of 10V, the joining strength average of the composite article 1 is 80N. When applying a voltage of 20V, 30V, 40V, and 50V, the joining strength average of the composite article 1 is respectively 70N, 85N, 55N, and 50N. Although the surface of the magnesium material 2 is deteriorated when applying a voltage of only 10V or 20V, there is no deterioration when the applied voltage is higher than 30V. Hence, this kind of electrolyte solution under a voltage between 10V and 50V can provide stable joint of the resin component 4. Additionally, the electrolyte solution in the embodiment is partly crystallized in the electrolytic bath. It is deemed that this phenomenon is due to excessive quantity of the mixture of sodium dihydrogen phosphate and sodium bicarbonate comparing, to the pure water 401, so that the electrolyte solution is already saturated.

From the above results, such as the embodiment shown in FIG. 5A, under the condition of mixing sodium dihydrogen phosphate alone with pure water to form the electrolyte solution, an anodic oxide film 3 suitable for producing the composite article 1 cannot be generated. It is deemed that the reason is the dissolution of the surface of the magnesium material 2 under treatment is faster than the generation of the anodic oxide film 3, such that a larger proportion of the surface of the magnesium material is removed, and the surface is consequently deteriorated. This phenomenon is particularly obvious when the applied voltage is low. On the contrary, when the applied voltage increases, the generation speed of the anodic oxide film 3 is boosted, and the deterioration of the surface of the magnesium material 2 is controlled by the generation of the anodic oxide film 3.

Furthermore, as shown in the embodiment of FIG. 6A, the anodic oxide film 3 generated through an electrolyte solution formed by mixing sodium hydroxide only with pure water cannot provide a stable and sufficient joining strength.

In contrast, as shown in the embodiments in FIG. 6B and FIG. 7B, the addition of sodium dihydrogen phosphate in sodium hydroxide can help generate an anodic oxide film 3 suitable for producing the composite article 1. It is deemed that sodium dihydrogen phosphate added in sodium hydroxide can act as a regulator to adjust the dissolving speed of the magnesium material 2, and to adjust the balance between the dissolution of the surface of the magnesium material 2 and the generation of the anodic oxide film 3, therefore helping generate an anodic oxide film 3 with sufficient joining strength.

Furthermore, under a condition that the weight of sodium dihydrogen phosphate dissolved in pure water is not too much more than that of sodium hydroxide, a stable joining strength can be obtained. The weight ratio R1 between sodium dihydrogen phosphate and sodium hydroxide is 1:2≦R1<2:1. However, an ideal weight ratio R1 is 1:1. Under this condition, the voltage applied on the magnesium material 2 is 10V or higher, ideally 10V˜50V. Based on this, it is possible to produce a composite article 1 with stable joint between the resin component 4 and the magnesium material 2 having sufficient joining strength.

In addition, the composite article in each embodiment can be applied in the components of electric or electronic appliances such as personal computer or mobile phone, or the interior and exterior fittings of building materials or buildings, or the interior and exterior fittings of ships, airplanes, railway cars, and automobiles, or decorative items like license plates, or any other composite article with magnesium material and resin component of any shape or any size.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrated embodiments and that the present invention may he embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and ail changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 

We claim:
 1. A method for producing a composite article of magnesium material and resin component, comprising the steps of: immersing a magnesium material into an electrolyte solution formed by dissolving sodium dihydrogen phosphate and sodium hydroxide in pure water; applying a voltage upon said magnesium material immersed with said electrolyte solution, so as to form an anodic oxide film on the surface of said magnesium material; and filling part of the resin component into the multiple pores on said anodic oxide film so as to join said magnesium material with said resin component.
 2. The method defined in claim 1, wherein the weight mixture ratio R1 of said sodium dihydrogen phosphate and said sodium hydroxide is 1:2≦R1<2:1.
 3. The method defined in claim 1, wherein the voltage applied on said magnesium material is 10V˜50V.
 4. The method defined in claim 1, wherein the weight proportion of said sodium dihydrogen phosphate and said sodium hydroxide is 1:1.
 5. A composite article of magnesium material and resin component comprising: said composite article made by the following steps: immersing a magnesium material into an electrolyte solution formed by dissolving sodium dihydrogen phosphate and sodium hydroxide in pure water; applying a voltage upon said magnesium material immersed with said electrolyte solution, so as to form an anodic oxide film on the surface of said magnesium material; and filling part of the resin component into the multiple pores on said anodic oxide film so as to join said magnesium material with said resin component.
 6. The composite article of claim 5, wherein the weight mixture ratio R1 of said sodium dihydrogen phosphate and said sodium hydroxide is 1:2≦R1<2:1.
 7. The composite article of claim 5, wherein the voltage applied on said magnesium material is 10V˜50V.
 8. The composite article of claim 5, wherein the weight proportion of said sodium dihydrogen phosphate and said sodium hydroxide is 1:1. 